USA or American Pattern - A 2.125", B 1.75", 1/4" Stud Hole also known as 3 on 2 1/2" (3 bolts at 2 1/2" apart measured from the outside of one stud to the outside of the next stud) Some American made karts

Metric - A 50mm (2"), B 40mm (1.5"), 8mm Stud Hole also known as 3 on 58 mm ( 3 bolts at 58mm apart measured from the outside of one stud to the outside of the next stud) Most European or CIK/FIA standard karts

CRG Front - A 60mm (2 3/8"), B 55 mm (2 3/16"), 8mm Stud Hole also known as 3 on 67mm (3 bolts at 67mm apart measured from the outside of one stud to the outside of the next stud) CRG front wheel pattern

Reading Go Kart Wheel Sizes:

Following each part number will be a description that might look like this:

8X8 3B+5N 4/110 .125 10MM

The first number refers to the wheel diameter, measured from the tire bead seat.

The second number refers to the wheel width, measured from the inside bead to inside bead.

The third number refers to the width of the inside half of the wheel, in this case in a BELL shape.

The fourth number refers to the width of the outside half of the wheel, in this case in a NOSE shape.

This 4/110 refers to the bolt pattern. It has 4 bolt holes, equally spaced around a 110 millimeter diameter circle.

This .125 refers to the thickness of the material used in the wheels, in this case .125 in. thick.

This 10MM refers to the size of the bolt hole, in this case 10 millimeters.